This invention relates generally to devices for illuminating otherwise nonilluminated instruments and gauges, and more particularly to an illuminating device having means for externally illuminating otherwise conventional instruments.
The illumination device herein disclosed is primarily designed for use in association with otherwise conventional scuba diving instruments that may include timers, compasses, depth and pressure gauges, thermometers, digital electronic instrumentation and any combination of these. However, the invention is not to be deemed as being limited soley to the applications just described.
Many compact, hand-held instruments are difficult to read in low light and dark conditions particularity those used in scuba diving. Instruments used in scuba diving give information of paramount importance to the diver. Divers must monitor these instruments many times throughout the course of a dive, in order to keep the dive within its limits. Therefore, a diver should be able to read an instrument with just a glance, but this is not always possible. While diving in low light and dark conditions scuba diving instruments are extremely difficult to read. In fact, many of the advanced digital instrumentation with liquid crystal displays, LCDs, are even difficult to read while using a hand held diver's light. These LCD instruments require a certain lighting angle. Achieving this angle of illumination is usually inconvenient for the diver.
Diving in low light or dark conditions is not uncommon. In fact, diving in the oceans at night is very popular. Night diving gives the diver the opportunity to observe nocturnal creatures of the underwater world. Additionally, divers frequent underwater caves, caverns and ship wrecks all of which provide extremely dark conditions if penetrated or if the dive is made during the night time. While diving in such conditions, divers carry special lights. These lights are designed and adapted for use underwater and they sufficiently illuminate the divers surroundings. Even though it is common practice for a diver to illuminate the instrumentation with this source of external lighting, it is not always effective and convenient.
Scuba divers rely on their instrumentation to monitor the state of the dive. When a diver makes a descent the depth gauge and timer can be used to calculate the rate of descent. The depth gauge will tell the diver when the maximum desired depth has been reached. Once at depth, the diver may require the use of a compass to navigate. The pressure gauge gives the diver an indication of how much available air remains in the scuba tank throughout the course of a dive. The timer is important because time and depth must be interrelated to calculate decompression status. Finally, a diver must ascend from depth and this requires the diver to ascend at a proper rate to avoid possible lung overexpansion injuries. By monitoring the depth gauge and timer (or perhaps one of todays sophisticated dive computers) the rate of ascent can be calculated. The diver typically monitors the instrumentation with a single hand held console which may house all of the instruments. The console is normally attached to the high pressure hose in order to include the pressure gauge which measures air supply pressure. The high pressure hose runs from the scuba tank to the divers console.
Modern technology permits internal lighting to be incorporated with digital electronics. This is exemplified by the lighting features found in digital watches. Internal lighting features in diving instruments would not be desirable. LCDs found on diving instruments are sometimes much larger than the display of a watch; a light source that would illuminate this increased display size would have to be relatively powerful, causing a shortened battery life. Furthermore, many diving instruments contain extreme long life batteries that are permanently sealed into the instrument casing. This is done to maintain the water tight and pressure proof integrity of the instrument and reduce maintenance on seals. Because the additional electrical draw of an internal light would prematurely deplete the actual life of the instrument, internal lighting would be undesirable. Some of the modern digital instruments will allow the user to replace the batteries. This feature is offered in certain instruments because they were intended to be turned on and remain on for extended periods of time. An internal light in this type of instrument would be more possible, because of the increased surplus of electrical power, but still would be undesirable because battery charge intervals would be increased. Every time a battery charge is made a battery compartment must be opened, and before it is reclosed the seals and sealing surfaces must be maintenanced. The increased battery change and maintenance requirements are not desirable. Furthermore, it is well known that if a seal worked for a previous dive the seal will work for the second dive, if the seal has not been tampered.